This invention relates to an adaptor plug and connector which facilitates substitution of an external automotive battery for the standard internal batteries which supply power to a hand-held power tool of the type having an elongated internal vertical housing in a handle with opposed vertical electrical housing contacts carried adjacent respective opposed vertical side walls of the housing.
As is well recognized in the art, conventional dry cell batteries have a short life in a device such as a hand-held power tool, especially when such a tool is frequently in use. The short battery life necessitates frequent battery replacement and consequent high costs, an annoying operating limitation. Moreover, although rechargeable batteries, such as those comprised of a nickel-cadmium alloy, sharply reduce the need for replacement, they require frequent recharging. Additionally, such batteries have a short shelf-life so that the electrical power therein dissipates relatively rapidly when in desuetude.
Various devices exist for substituting for power supplied by dry cell batteries, including that illustrated in U.S. Pat. No. 3,308,419, which shows a power supply means featuring a battery-shaped connector having helical contacts mounted thereon. Such a device, however, lacks means to guide and position same snugly within the elongated vertical housing of a power-operated tool or instrument; further, the helical contacts are not configured to engage the above-described vertical contacts within an elongated vertical housing. U.S. Pat. No. 4,946,396 illustrates a similar device, suitable for insertion into a rectangular battery box, wherein two contact holders at their respective ends each carry a retractable, cylindrical contact. Each contact is configured to cooperate with circular contacts in the battery holder of the power-operated device as a result of the positioning of a pair of foldable plugs which carry respective contacts. However, the shape cf such contacts renders the disclosed device unsuitable for engaging opposed vertical housing contacts within the battery compartment of a hand-held power tool. Finally, devices such as that disclosed in U.S. Pat. No. 4,835,410 feature a combined corded/cordless system for power-operated tools, but contemplate only internal batteries for supplying the DC power source, rather than an external automotive battery.
Accordingly, it is an important object of the invention to provide a hand-held power tool capable of being powered either by internal batteries or alternatively by an external automotive battery.
Another important object of the invention is to provide an adaptor which cooperates with diametrically opposed electrical vertical contacts carried within an elongated vertical housing.
Another important object of the invention is to permit the substitution an alternative DC power source for the internal batteries in a hand-held power tool having diametrically opposed electrical vertical contacts carried within the elongated vertical housing of the tool.
Still another important object of the invention is to provide an adaptor which includes longitudinally spaced conforming members to aid in guiding and positioning the adaptor within the battery housing of a hand-held power tool.